Electron-tube voltage regulator



Feb. 2 1926.

P. T. WEEKS ELECTRQN TUBE VOLTAGE REGULATOR Original Filed Apiil 25,- 1920 lNVENTOR Fax/Z T We/vo ATTORNEY WITNESSES:

Patented Feb. 2, 1926.

"UNITED STATES PATENT OFFICE.

PAUL '1. WEEKS, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTINGHOUSE LAn COMPANY, A CORPORATION OF PENNSYLVANIA.

ELECTRON-TUBE VOLTAGE REGULATOR.

. Application filed April 23, 1920, Serial No. 875,929. Renewed January 7, 1926.

To all whom it may concern:

Be it known that I, PAUL T. Wrens, a citizen of the United States, and a resident of East Orange, in the county of Essex and State of New Jersey, have invented a new and useful Improvement in Electron-Tube Voltage Regulators, of which the following is a specification.

invention relates to voltage regulating apparatus of the electron-tube type and it has for its object to provide apparatus of the character designated that shall permit the regulation of the voltage of alternating-current systems with a minimum of apparatus of simple form and arrangement, the system being particularly advantageous in that no moving parts are employed. In the accompanying drawing, Fig. 1 is a diagrammatic View tein embodying my invention; Figs. 2 and 3 are vector diagrams illustrative of the act on in the system of Fi 1; and Fig. 4: is a View similar to Fig. 1 and illustrating a modification thereof.

Electron tubes are well known of the type wherein a hot cathode is opposed by a cold anode, thecurrent flow between these electrodes being determined, aside from the plate potential, by the temperature of the cathode and, consequently, by the number of elec trons emitted thereby. Thus, where the cathode is heated by an electric current, a pronounced relaying action is obt a1ned, an increase in the heating current increasing the electron flow and the plate current and conversely.

It has been proposed to use tubes of this type in the regulation of the output voltage of variable-speed, direct-current generators, as used to supplythe energy for wireless sets in air-plane service, In this type of installation, an increase in the generator voltage increases the filament voltage and, consequently, the filament temperature, permitting an enhanced plate current to flow through an opposing field winding, thus maintaining the output voltage of the generator substantially constant.

In accordance with the present invention, an alternating-current-supply system of variable voltage supplies energy to a load circuit which it is desired shall be maintained at constant voltage. Furthermore, an electron tube of the hot-cathode type is of a regulating sysemployed, having its cathode temperature determined by the supply voltage and having its plate current flow through a trans former in such manner as to buck or oppose a transformer winding energized directly from the supply. By this means, a differential effect is produced, an increase in the voltage of the supply increasing the buck ng voltage and thus maintaining substantially constant voltage on the load circuit, as is desired.

Not only may my system be employed to minimize or smooth out voltage peaks in a system, as described, but it may becaused, by a reversal in function of certain elements, to accentuate voltage variations in a system, as, for example, in the magnification of minute variations for the indication and measurement thereof.

Further details of my invention will hereinafter more fully appear.

Referring to the drawing, I show alternating-current supply mains at 55, the voltage thereacioss Varying either too much or too little for application to a load circuit 6-6.

An auto-transformer winding 7 is com nected across the supply mains 55. The primary winding 8 of a transformed 9 is connected across a portion of the auto-transformer 7, and the secondary winding 10 thereof is divided into two portions 11 and 12. Two electron tubes 13 and 14 are provided, each having incandescing cathodes 15 and plate anodes 16. The filamentary cathodes 15-15 are connected across the portion 11 of the secondary winding of the transformer 9 through an adjustable resistor 17. The anodes 16-16 are connected to the mains 55 through the respective primary windings 18 and 19 of a transformer 20 having a single secondary winding 21.- The portion 12 of the secondary winding of the transformer 9 is connected in series relation with the secondary winding 21 of the transformer 20 for the energization of the load circuit 6, these two windings being connected in opposition and the electromotive force of the Winding 12 at all times predominating over that of the winding 21.

Having thus described the arrangement of a system embodying my invention, the elementary operation thereof is as follows. Assuming the application of an alternating electromotive force to the mains 5- -5, the transformer 9 is energized and the filaments 15-15 are raised to incandescence. -At the same time, an electromotive force is produced in the winding 12 for application to the load circuit 6.

The incandescence of the filaments 15- 15 permits the flow of plate current from the mains.55 through the primary w1ndings 18 and 19, an impulse flowing in the winding 18 and the tube 13 w1th supply waves of one polarity and an Impulse owing through the Winding 19 and the tube 14 with supply waves of the other polarity.

Thus, when the instantaneous polarity of the mains is such that the mam 5 1s positive, the plate 16 of the tube 13 will be at a higher potential than the filament 15 and the current will therefore flow from posltive main 5 through winding 18 and tube 13 to the negative cathode 15through the resistance 17 and thence to the middle tap or neutral point of auto-transformer 7. Expressing this in terms of electron flow; when the main 5 is positive, the middle tap of auto-transformer 7 will be negative with respect thereto andelectrons will flow from this middle tap through resistance 17 to a hot cathode 15 of tube 13 through the evacuated space to anode 16 and through the winding 18 to the main 5.

When the polarity of the mains 15 reversed and the main 5' is instantaneously ositive no current will flow through windmg 18 because the tube '13 only permits afiow in one direction, but current will flow from the positive main 5' through the winding 19 to the plate 16 of tube 14 to filaments 15 and resistance 17 back to the middle tap of auto-transformer 7. Expressed in terms of pure electron flow, instead of as positive current flow, the electron flow is just the reverse of the positive current flow, as described in connection with the situation when the main 5 is positive. It will therefore be apparent that tube 13 regulates the current impulses in one direction whereas tube 14 regulates those in the opposite direction because each tube only transmits current impulses in one direction. A

The magnitude of the current impulses varies with the electron emission of the cathodes 15 and, accordingly, with the voltage of the mains 5-5. The alternate flow of impulses in the windings 18 and 19 produces an alternating flux through the secondary winding 21,v producing an electromotive force therein in opposition to the electromotive force of the main supply winding 12. Thus, as the voltage of the mains 5-5 rises, the plate current through the tubes increases, increasing the electromotive force of the winding 21, thus neutralizing the increased electromotive force produced in the winding 12. Thus, by adjustment of the relative numbers of turns in their respective windings, the regulation of the circuit 6' may be adjusted, as desired.

It is well known that, with electron tubes, there is a certain critical'voltage that must necessarily be applied between the electrodes before a marked electron flow takes place therebetween. By adjustment of the relative numbers of turns so that voltage between the electrodes in the tubes shown is just below the critical value when the electromotive force of the mains 5 is at a minimum value, an extremely sensitive ar- I ran ement is provided.

urning now more specifically to the eration of the system shown, the vector in Fig. 2 represents the line voltage of the supply, and the vector E represents the back electromotive force of the primary windings 18 and 19, the vector E representing the volta e dro across the corres 0nding tube. 0 vious y, the lag angle between the vectors E and E, is determined by the ratio of resistance to inductance in the circuit through the tube.

Turning to Fig. 3, the vector E re resents the main electromotiveforce supp ied to the load circuit from the secondary winding 12, being in phase with the vector E of Fig. 2. The vector E, represents the opposing electromotive force of the secondary winding 21 and is not in strict 0 position to the vector E branching out t erefrom at an angle L determined by the ratio of reactance to resistance in the circuit in question and, therefore, approximately e ual to the angle L in Fig. 2. The vector it, represents the resultant electromotive force applied to the load circuit and to the secondary winding 21, being the vector difference between the vectors E and E When the voltage of suppl is increased, as to a point 22, as indicated y the dotted lines, the vector E eilz pands to a length E}, and the resultant may be rendered equal to E or ma be caused to increase or decrease by suitab e design of the. apparatus and of the relative number of turns therein. Obviously, the angle L should be of considerable magnitude; that is to say, the resistance of the corrective circuit should be comparable to the reactance thereof in order to secure a sensitive regulatingefl'ect.

Referring now to Fig. 4, certain of the windings of Fig. 1 are shown consolidated. Thus, the supply mains 5 are connected to the terminals of an auto-transformer winding 7 having taps 23, 24, 25 and 26 thereupon. A single electron tube 7 is employed having a cathode 28 and anodes 29'and 30. A transformer 20 is provided, as before, having primary windings 18 and 19 and a secondary winding 21. The anodes 29 and 30 are connected to the respective supply mains through the primary windings 18 and 19, and the filamentary cathode 28 is connected between the taps 24 and 25.

The main electromotive force for'the energization of the load circuit 6 is taken from the taps 23 and 26, and the secondary Winding 21 is included in this circuit to exercise an opposing regulating effect in accordance with the activity of the tube 27, as before. By appropriate adj ustmentof the number of active turns in the different windings, the tube 27 may be caused to operate at its critial voltage, as in the system of Fig. 1. Obviously, by reversing theconnections to the coil 21 (Fig. 1 and Fig. 4) the voltage induced in this coil may be added to the voltage supplied to the load circuit directly from the source and the percentage variations in the load voltage thereby increased over those occurring .in the line voltage as may be desired. The direction of the vector in Fig. 3 would be accordingly reversed in this case.

Thile I have shown my invention in its preferred form, it will be obvious to those skilled in the art that it is not so limited but is susceptible of various minor changes and modifications without departing from the spiritthereof, and I desire, therefore, that only such limitations shall be placed thereupon as'are imposed by the prior art or as are specifically set forth in the. appended claims.

I claim as my invention:

" .1. In a regulating system for ensuring the supply of a substantially constant electromotive force to a load circuit from a supply circuit of variable electromotive force, the combination with major energizing means for supplying an electromotive force to said load circuit directly from said supply circuit, of minor energizing means for developing an electromotive force variable with the electromotive force of said supply circuit but magnifying percentage variations in said electromotive force, and means for opposing the resultant electromotive force to said major energizing electromotive force in the load circuit.

2. In an electrical regulating system, means for supplying substantially constant electromotive force to a load circuit from a source of supply of variable electromotive forcecomprising a direct energizing connection for supplying a major energizing electromotive force to said load circuitdirectly from said supply circuit. an electron tube connected to provide an electromotive force variable with the electromotive force of the supply circuit but greatly magnifying percentage variations therein, and means for supplying an output electromotive force of said tube as a minor opposing force in the energization of said load circuit, whereby the effects of varying potential in the supply circuit are largely compensated for in said load circuit.

3. In an alternating-current regulating system, thecombination with an alternatingcurrent supply of variable voltage, of an alternating-current load circuit which it is desired to maintain at substantially constant voltage, transformer means for producing a major energization of said load circuit directly from said supply circuit and proportional to the electromotive force thereof, rectifying electron tubes having filamentary cathodes the temperature of which varies with the supply electromotive force, Whereby the plate currents of said tubes also vary with the supply electromotive force but with a greatly magnified percentage variation, and further transformer means for inducing from said plate currents an electromotive force in said load circuit in opposition to the main energizing electromotive force thereof, whereby the effects of voltage variations in the supply circuit are largely neutralized in the load circuit.

4:. In an alternating-current regulating system, the combination with an alternatingcurrent supply circuit of variable voltage, of a load circuit the voltage of which it is desired to maintain substantially constant. transformerqmeans for energizing said load circuit directly from said supply circuit, an electron-tube structure embodying a filamentary cathode and cold anodes, means for energizing said cathode to incandescence and variable with the electromotive force of said supply circuit, transformer means comprising primary windings in circuit with the respective anodes and a secondary winding in series with said load circuit, and connections from said last-named primary windings to the supply mainswhereby, upon an increase in the supply electromotive force, an enhanced electromotive force tends to be supplier directly to the load circuit and the temperature of said filamentary cathode is increased with an attendant increase in the anode currents and an enhanced electromotive force is established in said last-named secondary winding in opposition to the energizing electromotive force of said load circuit, whereby the effect of voltage variations in the supply circuit on the load circuit is substantially eliminated.

In testimony whereof, I have hereunto subscribed my name this sixth day of April, 1920.

PAUL '1. WEEKS. 

